"We hold that portions of the @realDonaldTrump account -- the “interactive space” where Twitter users may directly engage with the content of the President’s tweets -- are properly analyzed under the “public forum” doctrines set forth by the Supreme Court, that such space is a designated public forum, and that the blocking of the plaintiffs based on their political speech constitutes viewpoint discrimination that violates the First Amendment," Buchwald wrote.

She added, "While we must recognize, and are sensitive to, the President’s personal First Amendment rights, he cannot exercise those rights in a way that infringes the corresponding First Amendment rights of those who have criticized him.

"The President presents the @realDonaldTrump account as being a presidential account as opposed to a personal account and, more importantly, uses the account to take actions that can be taken only by the President as President," the judge said.

After a hearing this year, the judge had suggested that Trump mute rather than block some of his critics. At the time, a Justice Department attorney agreed that muting would enable Trump to avoid a tweet he doesn't want to read.

Twitter users can block people, which prevents them from seeing the user's feed while logged in. Or they can mute the person, which keeps the user from seeing that person's tweets and reply messages in their feed.